1. Field of Invention
The present invention relates to weighing machines, and more particularly, is directed towards weighing machines with digital displays
2. Description of the Prior Art
Many weighing machines or scales which have been designed with digital displays have been introduced with varying degrees of success. A digital display weighing machine is shown in U.S. Pat. No. 3,853,191. In scales having an indicator disc or pointer mounted to a rotatably shaft, one approach is to connect an analog type position detector, such as a potentiometer or other encoder, to the shaft and to convert the angular shaft position to a decimal output by means of an analog to digital converter. This approach has the disadvantages that, in addition to the analog to digital converter circuitry being complex and costly, the position detector imposes drag on the system and impairs its accuracy. Another approach is to provide photo-electric detectors for sensing the angular position of a coded disc mounted to the shaft. A unique pattern provided on the coded disc is sensed for each disc position. This approach has the disadvantage that it requires a multiplicity of sensors in order to convert the code to a digital display. Still a further approach is to sense the direction of disc rotation and to specify the digital value of the final disc position by employing up/down counters. This approach has the disadvantage of requiring complex and costly sensing devices and circuitry.